title: Effects of drinking water with high iodine concentration on the intelligence of children in Tianjin, China.
abstract: OBJECTIVE
  This study aimed to investigate the effects of drinking water with high concentrations of iodine on the intelligence of children in Tianjin, China.
  
  
  METHODS
  It was a population-based health survey utilizing a random cluster sampling design conducted in June 2005. Participants were recruited from the total population of primary school children attending years 1-4 with ages ranging from 8 to 10 years. Intelligence quotient (IQ) was assessed using the combined Raven's test, second edition. Linear regression analyses were applied to test for any association between water iodine concentration and IQ.
  
  
  RESULTS
  A total of 1229 students were recruited with a mean IQ of 105.8 (95% CI: 104.2-107.3). Water analyses indicated iodine concentrations were high in one rural region and exceedingly high in another with median values of 137.5 and 234.7 microg/l, respectively. There was a significant association between residing in the very high water iodine region and a reduction of IQ by an average of about nine points (P = 0.022), after adjusting for the potential confounding factors.
  
  
  CONCLUSIONS
  Exposure to high iodine concentrations in drinking water has detrimental effects on the intelligence of children.
authors.affiliation: Tianjin Centers for Disease Control and Prevention, 76 Hualong Road, HeDong District, Tiahjin 300011, People's Republic of China. hongliang.liu@sina.com
authors.forename: Hong-Liang
authors.initials: HL
authors.lastname: Liu
authors.forename: Lawrence T
authors.initials: LT
authors.lastname: Lam
authors.forename: Qiang
authors.initials: Q
authors.lastname: Zeng
authors.forename: Shu-qing
authors.initials: SQ
authors.lastname: Han
authors.forename: Gang
authors.initials: G
authors.lastname: Fu
authors.forename: Chang-chun
authors.initials: CC
authors.lastname: Hou
mesh_terms: D002648:Child; D002681:China; D005260:Female; D006306:Health Surveys; D006801:Humans; D007360:Intelligence / Q000187:drug effects*; D007455:Iodine / Q000009:adverse effects / Q000032:analysis*; D008297:Male; D012111:Residence Characteristics; D014881:Water Supply / Q000032:analysis*
chemical_list: D007455:Iodine